Paleomagnetic constraints for the tectonic evolution of the southern Apennines belt (Italy)

The southern Apennine belt is formed by nappes that have undergone large (i. e. hundreds of kms) horizontal displacements. In such tectonic scenario, orogenic rotations of nappes are clearly expected, and paleomagnetism may represent a key tool to constrain displacements and understand the pre-orogenic paleogeography. Recent paleomagnetic data have shown that the Apenninic carbonate platform, on top of the nappe pile, has rotated ~80° counterclockwise (CCW) after Langhian times. A similar rotation may be inferred for the Lagonegro basinal unit. Numerous data from the Plio-Pleistocene sediments unconformably overlying these two units reveal a 0°-40° (20° on average) CCW rotation since early Pliocene. Data from the exposed Apulian swell, and from other parts of the Adriatic plate, suggest that the buried Apulian platform has not undergone a significant rotation. Therefore the overall paleomagnetic/ geological data suggest that during mid-late Miocene the Apenninic platform and Lagonegro unit were detached from basement, underwent internal imbrication associated with a 60° CCW rotation. During early-mid Pliocene, this wedge was carried over the Apulian carbonates (which were in turn internally stacked in late Plioceneearly Pleistocene times), and underwent a final 20° CCW rotation. The paleomagnetic data also prove that the southeastward drift of Calabrian block (and synchronous spreading of the southern Tyrrhenian Sea) induced oroclinal deformation of the southern Apennines and Sicily, which underwent similar-magnitude (but opposite in sign) orogenic rotations. Relying on such rotational pattern, we propose a paleogeographic reconstruction for late Langhian (and older) times characterized by the presence of a NNE-oriented narrow carbonate platform corridor separating the Ionian and Liguro- Piedmont oceans.Published39-463.4. GeomagnetismoJCR Journalreserve